Tianwen 1 (Mars mission)

  • Tianwen 1, China's Mars mission which launched today


    The was minimal information regarding the frequency and ephemeris. Thanks to uhf-satcom for finding it this morning.


    8430.867 = 21.4 MHz, wide spectrum inverted, narrow non-inverted

  • Thanks a lot s-band for your contributions in this frequency range .


    There are many "Mars mission" @ the moment ?!

    - Wineguard Micromesh 3.10 m
    - Channel Master PFA 3.10 m
    - Laminas 1.80 m
    - 2 X Channel Master 1.80 m
    - Channel Master 2.40 m
    - KU, KU Ext.,Full KA, X, C & C Ext
    - TBS5925 -TBS6522 - TBS6983 - DTA2137CSXP
    - NS2000 - RX8200 - ADV-6000S
    - TM1 - TC1 - SR1 - MATRIX DEV1982
    - Promax TV II+ - SMR1224EL x2
    - ASC1 X2 - RC2000C - EGIS - LNB Changer
    - 76.5°E <> 65°W
    - Loc: France

    ...


  • Quote

    Original von Feedsat
    Thanks a lot s-band for your contributions in this frequency range .


    There are many "Mars mission" @ the moment ?!


    You're welcome. This one was a difficult one as the Chinese did not release much information. Thanks to uhf-satcom and others on #hearsat IRC channel for their help.


    https://mars.nasa.gov/mars2020/ carrying Perseverance Rover is due to be launched on 30th July.

    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • 8430.907 = 21.4 MHz, wide spectrum inverted, narrow non-inverted


    The first plot has averaging set to 64. The slope is due to the IF response of the RX.

  • 8430.907 = 21.4 MHz, wide spectrum inverted, narrow non-inverted


    Not strong enough to see the sidebands now. Thanks to DF2MZ for all the work on the tracking co-ordinates.

    Images

    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Tianwen switched to the high gain antenna at around 00:30 UTC this morning. It is now very strong at -115.7dBm at the feed of the 1.2m dish.


    Edgar, DF2MZ https://twitter.com/df2mz, has collated and processed tracking data to produce very good celestial co-ordinates. Tianwen was at about 1.2 million km from Earth this morning according to calculations by Daniel Estévez https://twitter.com/ea4gpz. Thanks to everyone involved in this.

  • Daniel Estévez has posted tracking data here Thanks to everyone involved in this project.


    It appears to have increased in signal by about 8dB in the last couple of days. I need to re-calibrate as the power increase reported was about 5 dB yesterday.


    The channel power plots show the total power in a couple of bandwidths. The noise level was -113.33dBm in 1.25MHz and -122.24dBm in 165kHz.

  • Thanks to the efforts of amateur optical and radio observers, the ephemeris data is now very accurate. JPL have added it to the Horizons database with this identification: Tianwen-1 (spacecraft) [-9901491]

    Links to latest information:

    Daniel Estévez Twitter

    Achim Vollhardt Twitter

    r00t.cz Twitter


    TW1 has 2 pairs of sidebands which have the same structure and modulation as the main signal. It's hard to believe they are spurii, more investigation needed. Today the levels, on a 1.2m dish, were:

    8407.914 -137dBm

    8411.747 -124.6dBm

    8430.907 -111dBm

    8450.007 -124.6dBm

    8453.897 - 139.2dBm

    The main signal, on 8430.907 (+/- Doppler). Here are the 4 sidebands:


    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Now at about 3 million km and still very strong, -112.6dBm using a 1.2m dish.

    See Daniel Estévez TCM1 blog post about the first correction manoeuvre.


    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Waterfall shows AOS from low easterly horizon, hence the increasing signal. You can see thermal noise drop off as the green stuff leaves the dish beamwidth. The markers are the top 4 signals within the bandwidth.


    regards,


    Paul.

  • Thank you Paul for your answer.

    I agree with you about the change in amplitudes due to the rise of the satellite above the horizon.:73:



    As for the fact that the false "signals" (numbered from 1 to 8) are associated with the local oscillator subharmonics, which are observed with a constant frequency step at the waterfall, I remain unconvinced. This is also evidenced by the regular change in their amplitudes.

    On what basis did you select the signal ?, which is marked with a blue marker, I do not understand ... :25:

  • Here are today's plots with TW1 at about 5Mkm from Earth.


    strannik Hi, The odd harmonics of the down-link sub-carrier are most likely to be due to it being modulated as a square wave. I always seem to miss the times when the up-link loop-back spectrum is present. That's seen as the close in lines on Paul's plot. I think that Spectravue is automatically highlighting the highest 4 peaks for that snapshot, Paul will correct me if I'm wrong. The overall spectrum of Tianwen is a little messy. It's hard to know if some of the signals are intentional, possibly for long base-line interferometry.


    r00t.cz has posted details of the modulation and decoding here




    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Hello s-band !

    I also believe that when the transmitter operates in saturation mode on long-distance communication lines, a rectangular, square wave-like signal has a high level of odd harmonics. This is evidenced by a regular, quasi-hyperbolic decrease in their amplitudes.

    But it would be wrong to consider them as "signals" ...

    Interferometry has nothing to do with it, IMHO :28:

  • But it would be wrong to consider them as "signals" ...

    Interferometry has nothing to do with it, IMHO

    Sorry, I was referring to the 4 other signals, which carry the same data stream as the main one. If you remove the differential Doppler and take into account that the frequencies were measured over a period of about 30 minutes, they seem to be at multiples of 500kHz from the main carrier.

    RE: Tianwen 1 (Mars mission)


    Unfortunately we don't have any information from the operators so you may be right on the cause of the 65kHz sub-carrier's odd harmonics.

    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Still a very good signal at 21.6Mkm. NASA Horizons data has been updated following the TCM-2 burn.

    https://destevez.net/2020/09/tianwen-1-tcm-2/

    Images

    1.2m Prodelin 1224 az-el with one of:
    S: Helical feed, 0.8dB NF LNA, X: 1.2dB NF LNA, conical feed,
    Ku 12-18GHz: corrugated conical feed, 1.5dB NF LNA, Ku (Standard): Octagon OSLO mod for C120 & ext ref Prodelin feed.

    Ka: Gilat ex-ODU PLLs Gilat feeds, Ka 18-26.5GHz: Patriot feed, home made 4dB NF LNA, Ka DSN: Corrugated conical feed, home made 3dB NF Down-Converter

    1.5m IRTE, Polar mount with Octagon OSLO mod. C120, IRTE feed
    40km East of London, UK

  • Here is my very first acquisition of Tianwen-1 on open waveguide pointing about 220deg. As this point the signal frequency was unknown so it had to be found by brute force. Doppler shows spacecraft approaching me. Launched 23 July 2020, 04:41:15 UTC and I detected it at 23 July 2020, 06:01:04 UTC not bad ;-)


  • Almost twice the distance, at 41.8Mkm, compared to my last post. Still very strong at -132dBm at the feed of the 1.2m dish with the modulation still visible.

Participate now!

Don’t have an account yet? Register yourself now and be a part of our community!